Apparatus for pulverizing materials



May 28, 1929. w.-'r. DOYLE APPARATUS FOR PULVERIZING MATERIALS 2 sheets sheet l Filed Oct. '1, 1928 INVENTORI W, ATTORNEY May 28 1%29. w, T DOYLE 1,735,323

APPARATUS FOR PULVERIZING MATERIALS Filed Oct. 1, '1928 2 Sheets-Sheet 2 INVENTOR 1 M ZZOAZTETZORNEY' Patented May 28, 1929.

UNITED STATES PATENT oFFlc WILLIAM T. DOYLE, OF BOSTON, MASSACHUSETTS, ASSIGNOR T STURTEVANT MILL COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

APPARATUS FOR PULVERIZING MATERIALS.

The invention to be hereinafter described relates to apparatus for grinding or reducing materials.

Many natural and manufactured materials vary in their degree of hardness, and the harder the material the more diflicult it is to grind it. A grinding machine for maximum efficiency should have uniform rate of feed to the machine, uniform fineness of the ground product, and maximum output. However, owing to the varying degree of hardness of the material, it is usually necessary to make provision for varying the rate of feed of material to the machine. Grinding machines are equipped with various types of feeders, but they are usually not capable of nicety of regulation, land'hence variations in feed are objectionably large. In machines requiring a short time in reducing materials, increase in the rate of reduction of the materials occurs rapidly and can be promptly noted, but in machines requiring a long time in reducing materials, such as are employed for high tonnages, increase in the rate of reduction of the materials is on such a large scale that it has been difficult to handle.

A purpose ofthe present invention, therefore, is to provide means to regulate the feed of unground material to the mill automatically in response to variations in the frangibility of the materials being ground. The regulation is such that onincrease in hardness of material above normal, the speed of the feeding means will be reduced or it will 5 be arrested, and on decrease in hardness of material, the feeding means will be started or its speed will be increased, to the end that the material may be reduced by the mill with uniform fineness of product and with maximum output.

Heretofore an operator has been relied upon to regulate the feed of unground material to the mill, but he acts to a large extent by guesswork, and is liable to over increase or decrease the feed. and in either case with too much delay. The automatic regulation accomplished by the present invention eliminates the necessity for the operator and insures proper regulation of the feed.

In the present instance of the invention,

the apparatus comprises a ball tube mill which may have one or more compartments or stages of reduction. The mater al to be reduced is fed into one end of the mill, and the ground material is delivered from the opposite end of the mill and conveyed to a separator which i may be an air or a screen separator. The tailings delivered by the separator are returned to the mill for further reduction. If the hardness of the material remains uniform, the material will be reduced at a uniform rate in the mill, will be delivered at a uniform rate from the mill, will be conveyed at a uniform rate to the air separator, and the tailings will be returned at a uniform rate to the mill. On the other hand, if the hardness of the mate rial increases, the rate of reduction will be lowered, there will be a larger percentage of tailings coming from the separator, and unless the rate of feed of materials to the mill is reduced or the feed is arrested, the tailings returned to the mill will build up therein and result in variation in the degree of fineness of material reduced, and if the building up be rapid enough, it will exceed the amount which can be delivered through the orifices of the mill or overfill and choke the mill causing stoppage.

The variations in the stream of tailings or rejects passing from the separator to the mill are utilized in the present instance for automatically regulating the feed of unground material to the mill. 1 To accomplish this, this stream is conducted through an orifice which may have a predetermined opening adjusted suitably for the normal capacity of the machine, and if the materials be delivered to the orifice at a greater rate than can pass the same, they will build up back of the orifice. This action can be utilized to control the feed as will be hereinafter explained.

The character of the invention may be best understood by reference to the following deseription of one good form thereof shown in the accompanying drawings. wherein:

Fig. 1 is an elevation of the apparatus;

- Fig. 2 is a vertical section through the ball tube mill and a side elevation of the control hopper container;

Fig. 3 is a view showing the container in vertical section, the hopper therein in side elevation, and the control means actuated by the hopper in side elevation: and

Fig. 4 is a plan showing the mounting on the container of the tilting beam carrying the hopper.

Referring to the drawings, the apparatus shown therein as one good form of the invention, comprises a ball tube mill 1 (Fig. 1)

5 at opposite ends thereof. The head 3 has a hollow trunnion journalled in a bearing 5 mounted on a pier 7 on the foundation 9. The head 5 has a hollow trunnion journalled in a bearing 11 mounted on a pier 13 on the foundation.

The tube contains a primary reducing c0111- partment in the end portion 15, and a secondary reducing compartment in the end portion 17 thereof. These compartments have linings and contain suitable reducing medla which may be in the form of balls or other elements. The halls in the primary reducing compartment are larger than those in the secondary reducing compartment. Between these compartments is a division plate for automatically transferring materials reduced in the primary compartment to the secondary compartment. Since the internal construction of this ball tube mill is usual and well understood in the art, it is unnecessary to show and describe the same in detail herein.

Mounted on a frame 10 atone end of the tube is a feeder 21 which may be of the well known table type driven by an electric motor 23. The material is conducted from the feeder 23 by a chute 25 to the hollow trunnion of the tube head into the primary reducing compartment. It passes thence through the divlsion plate into the secondary reducing compartment. The material is delivered from the latter through the hollow trunnion of the head 5 to a hopper 27 provided with a screw conveyer 29 for conducting the material to the base of an elevator 31.

The material is conveyed by this elevator to an air separator 33, such, for example, as is disclosed in Letters Patent No. 1,615,558, granted in the name of Thomas J. Sturtevant, January 25, 1927. The fines may be conducted away from the separator by a screw conveyer at the lower end thereof, and the tailings or rejects may be conducted from the separator through a chute 37. c

This chute leads to a container or casing 39 of general conical form, and connected by a chute 41 with a housing 43 (Fig. 2) extend-.

ing over the ball tube mill and having a sump 45 at the base thereof. The tube provided with a pair of scoops 47 which on rotation of the tube automatically pick up material from the sump and transfer it into the tube. In the present instance the material is delivered by the scoops to the secondary reducing compartment of the mill.

Mounted within the container 39 is a receiver in the form of a hopper 49 (Fig. 3) having a receiving mouth 51 directly beneath the separator chute 37, referred to. At the lower end of the hopper 49 is a neck 53 having a discharge orifice 55 provided with a flap valve or gate 57 hinged to the neck and having an arm 59 with a bore therein threaded to a screw 61 having its inner end connected to the 110p- 3 and passes therethrough per and its opposite end projecting, through an opening in the container and provided with a hand wheel 63, the construction being such that the valve may be swung to vary the opening of the orifice and be held in its positions of adjustment.

Adjacent the upper end of the hopper are brackets 65 connected to the lower ends of links 67 which extend up through holes in the top of the container, and have hooks 69 connected to eyes 71 pivotally mounted on a beam 7 3 having a loop 74 encircling the neck 75 at the top of the container, to which the chute 37 is connected. The beam has a pair of trunnions 77 in bearings in brackets 79 mounted on the top of the container. Connected to the outer end of the beam is a rod 75 carrying aplate 77 on which a number of counterbalance weights 79 may be placed. The hopper, beam, rod and weights are in the nature of a weighing machine, the construction being such that when a sufficient weight of materials has entered the hopper, the beam will tilt in a contra-clockwise direction (Fig. 3).

The movements of the hopper, beam and rod may be utilized to control the motor 23 referred to, for the feeder 21. ,To accomplish this, a motor speed controller 81 may be provided of usual construction and effect .several speeds of the motor. This controller may be mounted in a box 82 on a support and be connected by suitable wiring with the motor. It has a rock arm 83 connected by a. link 85 with one arm of a bell-crank 87, the other arm of which has a fork 89 receiving a pin 90 on a block loose on the rod 75 referred to. Coil springs 91 encircle the rod and are confined betweenthe block and buttons 93 fa st on the rod. The construction is such that when a sufficient weight of material accumulates in the hopper 49, it will overcome the weights 79, rock the beam 73, shift the rod 75 upward, and the latter, through one of the springs, the bell-crank 87, link 85 and rock 'arm 83, will operate the controller so as'to reduce the speed of the feeder motor 23. On the other hand, when the accumulated material in the hopper 49 is discharged, the weight 79 will become effective to shift the rod 75 downward and increase the speed of the feeder motor. I

In some instances it may be desirable intermittently to start and. stop the feeder motor. To accomplish this, a switch 95 may be provided in the motor circuit, and may have an arm 97 under the control of buttons 99 on the rod 75, the construction being such that when the hopper moves downward sufficiently, the switch will be operated to open the motor circuit and stop the motor, and on the other hand, when the hopper moves upward sufficiently, the switch will be closed to start the motor. The up and down movementsof the hopper and the rod 75 may be the hopper valve will be adjusted for this condition. If the material runs above normal hardness,'the speed of the feeder motor will be reduced, or the feeder motor will be stopped, thereby to allow more time for the mill to reduce the harder material. \Vhen the material running through the mill is above normal hardness, a smaller percentage of the product delivered therefrom will be fines and a larger percentage of the materials graded by the separator will be tailings, which will be delivered from the separator in a stream greater than normal. This stream will flow into. the hopper 49, but since a greater amount of material than normal will be flowing therein, the orifice will not be able to pass all of it. As a consequence, material will back up and accumulate in the hopper and may fill the same. Then the weighing beam will tilt and operate the controller to reduce the speed of the feeder motor or arrest the latter and allow more time for the mill.

to grind the material. After the hopper is filled, materials continuing to pass thereto may flow over the edge of the hopper mouth and pass down through the container 39 and the chute 41 into the sump 45, and belifted by the, scoops 47 into the mill. When the stream of tailings again becomes normal, the accumulation in the hopper will pass through the orifice, and the hopper will rise and the beam will tiltthereby to throw the switch to start the feeder motor in case it Was arrested, and operate the controller to increase the speed of the motor for normal feed.

The orifice opening may be adjusted and the counterbalance weights may be such that the hopper will drop somewhat and tilt the beam before the hopper is filled. Thiswill result in one'or more stages of motor speed reduction. but will not stop the motor. Then if the tailings stream continues to increase beyond the ability of the orifice to pass it, the materials will further build up in the hopper and effect further speed reduction and possibly arrest of the motor.

The stream of tailings returning to the mill is relatively small as compared to the volume of the unground materials fed to the mill, and is quickly sensitive to variations in the degree of hardness of the material ground. Thus the character of the stream may be utiand that various deviations may be made therefromwithout departing from the spirit and scope of the appended claims.

What is claimed is:

1. The combination of a mill for reducing material, means for feeding material to the mill, a. separator for receiving material from the mill, means for conducting tailings from the separator to the mill including a receiver having a delivery orifice sufliciently large to pass a normal stream of tailings, and means to control the feeding means to reduce the feed of unground material to the mill on flow int? the hopper of a stream greater than norma 2. The combination of a mill for reducing material, means for feeding material to the mill, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill, and means responsive to variations in the stream of tailings for controlling the operation of the feeding means.

3. The combination of a mill for reducing material, means for feeding material to the mill, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill, and means responsive to at least a portion of the stream of tail-, ings delivered by the separator for controlling the-operation of the feeding means.

4. The combination of a mill for reducing material, means for feeding material to the mill, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill including a hopper having a delivery orifice suflic'iently large to pass anormal stream of tailings, a weighing beam carrying the hopper, and means actuated by the weighing beam on accumulation of a predetermined weight of material in the hopper for controlling the operation of the feeding means.

5. The combination of a mill for reducing material, means for feeding material to the mill, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill including a container, a hopper in the container having a delivery orifice, a Weighing beam carrying the hopper, a counterbalance weight carried by the beam, and means operable on accumulation of material in the hopper and consequent tilting of the beam for varylng operation of the feeding means.

6. The combination of a mill for reducing material, means for feeding materials to the mill, a separator for receiving material from the mill, means forconducting tailings from material, means for feeding material to the mill, aseparator for receiving material from the mill, means for conducting tailings from the separator to the mill including a hopper,

weighing means associated with the hopper, means operated by the Weighing means for controlling the feeding means, and a signal actuated by the weighing means for indicating regulation of the feeding means.

8. The combination of a mill for reducing material, means for feeding material to the mill, a separator for receiving material from the mill, means for conductingtailings from the separator to the mill including a hopper, weighing means associated with the hopper, and a controller operated by'the weighing means for varying the speed of the feeding means.

, 9. The combination of a ball tube mill for reducing material, means for feeding material to one end of the mill, a separator, an elevator for receiving material delivered from the opposite end of the mill and conducting it to the separator, means for returning tailings from the separator to the mill, and means operable in response to variations in the rate of flow of the tailings for controlling the feeding means.

10. .The combination of a mill for reducing material, means for feeding material to the null, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill, and means responsive to the rate of flow of tailings from the separator for automatically controlling the feeding means.

11. The combination of a mill for reducing material, means including an electric motor for feeding material to themill, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill, and means responsive to variations in the stream of tailings for automatically controlling the motor.

12. The combination of'a mill for reducing material, means including an electric motor for feeding material to the mill, a separator for receiving material from the mill, means for conducting tailings from the separator to the mill, and means responsive to variations in the stream of tailings for automatically starting and stopping the motor.

. 13. The combination of a mill for reducing material, means including an electric motor for feeding material to the mill, a separator for receiving material from the mill, means for conducting. tailings from the separator to the mill, and means responsive to variations in the stream of tailings for automatically varying the speed of the motor and starting and stopping the motor.

WILLIAM T. DOYLE. 

